In mechanical engineering, processing machines that chuck a rotary tool by means of an internal chucking unit are often used. The rotary tool hereby has a cylindrical socket, which corresponds to a mandrel on a tool holder of the processing machine. For the connection, the rotary tool is attached on the mandrel and is mostly secured from the front side of the tool holder by means of a screw connection. In order to be able to attach the socket on the mandrel, tolerances in the fit are required. However, as a result of these fits, a centric chucking of the rotary tool on the mandrel with a high accuracy is not possible, which leads to manufacturing errors or an increased wear on the rotary tool.
From the state of the art, various solutions for this problem are known. Thus, WO 2005/063426 A1 shows an internal chucking unit with a mandrel for the centering of a rotary tool with a socket. The mandrel has a segment chucking device with several rigid chucking segments that protrude radially outward. The chucking segments are supported on a conical surface such that a movement of the chucking segments in the longitudinal direction of the mandrel brings about a radial movement of the chucking segments in the direction of the rotary tool. Thus, the chucking segments can be employed on the socket, wherein the tolerance in the fit between the mandrel and the socket of the rotary tool is overcome and a good centric chucking is attained. In order to hold the chucking segments together and to support a loosening of the segment chucking device, the chucking segments are elastically connected by means of rubber elements.
From FR 2 297 107 A1, an internal chucking device for a rotary tool is also known. As also shown already in WO 2005/063426 A1, the internal chucking device is designed as a segment chucking device with several chucking segments, protruding radially outward, for the centering of the rotary tool. In contrast to the subject of WO 2005/063426 A1, a surrounding rubber ring is provided for the securing of the chucking segments.